Desenvolvimento de pães à base de farinha de inhame (Dioscorea cayennensis Lam.) obtidos por fermentação natural

Abstract

Yam, a tuber of the genus Dioscorea, is considered a subsistence crop and has great socioeconomic importance in the states of Northeast Brazil. It is a highly perishable tuber and a strategy to increase its shelf life is the production of flour from drying processes. Several studies have been performed in order to replace the wheat flour by flour from other sources for the production of bread, which are considered basic consumer foods in many countries. With the increase in the number of people with celiac disease, there is an increase in the market for gluten-free bakery products, however, the absence of gluten leads to undesirable characteristics of these products. One of the ways to get around this problem is the use of natural fermentation, that is, obtaining yeasts from the spontaneous fermentation of the mixture of water and wheat flour or from other substrates such as fruits and starchy matrices such as potatoes. With this, the objective of the research was to prepare breads with substitution of wheat flour for yam flour (D. cayennensis Lam.) Using two types of yeast, commercial and natural, the latter using potatoes as a substrate. The yam flour, obtained by two different drying methods (freeze-drying and convective drying), and the breads were analyzed for moisture, pH and acidity, lipids, proteins, Aw, color and ash parameters. The bread's antioxidant capacity was determined by analysis of the capture of the radical ABTS and DDPH. Microbiological analysis and acceptance test by consumers were also performed with the breads. The results obtained were submitted to two-way ANOVA and the means compared by Tukey's test at the level of 5% of significance. From the drying of the tubers it was observed that the drying method did not show significant difference for most of the analyzed parameters. Regarding the breads obtained by commercial and natural yeast, the results showed that the higher the level of substitution of wheat flour for yam flour, the lower the levels of lipids (3,88 and 3.43%) and proteins (3,26% and 2,73%), respectively. The high starch content in yam flour (73%) caused a decrease in the level of reducing sugars with the increase in the incorporation of yam flour into breads. On the other hand, when considering the antioxidant activity, the higher the level of substitution the greater the antioxidant power of the samples, in relation to the radical ABTS, the breads with 100% of yam flour had a capture capacity of 30,88 and 31,35 mol TE/g for commercial and natural yeasts, respectively. It was also observed that the type of yeast influenced the antioxidant capacity, since breads produced from natural fermentation had a higher percentage of capture in relation to the radical ABTS (80%). In the sensory analysis, the commercial yeast control breads and 50% of naturally fermented yam flour showed the best results with the tasters in all evaluated parameters. Such results, added to the evaluation of the sensorial analysis, allow to conclude that the use of natural yeast and the substitution of up to 50% of the wheat flour had a positive effect in obtaining a bread based on yam flour.